Resolution:
The administrator authentication phrase used by PowerChute Network Shutdown (PCNS) should be the same as that used in the NMC. The default used by the NMC is: admin user phrase.

The authentication phrase must be at least 15, but no more than 32 characters. You must use ASCII characters A-Z, a-z, 0-9.

Background:
If you change the authentication phrase in PCNS, you must also change it on the NMC (otherwise, PCNS and the NMC will not be able to communicate). If you are using a Redundant Smart-UPS, Multiple Symmetra, or a Parallel UPS configuration, all of the NMC authentication phrases must be the same.

Note: You can set the authentication phrase value in the NMC user interface.